Avebury Stone Circle
Acoustic research conducted here by John Crewdson has shown that sounds generated within the henge are contained by the earthen bank, and could not have been clearly heard from outside. Likewise, the interior would have been artificially quieter than the open landscape beyond, as sounds from the wider world are also blocked and filtered by the bank.
This sets up a clear distinction between the experiences of people. Anyone outside would have had very little knowledge of events within as they could neither clearly see or hear events in the interior.
It has also been suggested that some of Avebury’s massive standing stones were placed in specific areas, deliberately altering the acoustics within the henge.
AUDIO RECORDING OF AN "AVEBURY ECHO"
One can only imagine what sound effects were evident 5,000 years ago when this place was originally in use, there have been suggestions that the ground was cut back to the natural chalk, indeed the henge would surely have been. When inside the inner circle the echoes and resulting effects of this would have been quite astounding.
Within Avebury's earthwork, there are features that direct and control sound. The three large monoliths of the Cove act to screen the movement of sound in some directions, while allowing it to project outwards through its open side. Perhaps this feature acted rather like a stage in a theatre, enabling voices or other sounds to be more audible from certain directions.
It is obviously a possibility that the acoustic properties of Avebury came about entirely by accident. That is until you consider that the huge monoliths in the circle are actually smooth on one side, and that side is the one that faces inwards.
These echoes may well be just an accidental effect, but there is reason to suspect otherwise. William Stukeley, as early as 1720, noted that the stones of the Avebury circle were arranged with their smoothest sides facing the inside - as were the stones of the two inner circles.
Previous studies of circular features have shown a remarkable consistency between many sites:
One of the most interesting aspects of circular spaces is the way in which echoes change dramatically in relation to the locations of the listener and the sound source. If both are close to the centre, sounds will be reflected simultaneously from all sides of the circle and return as a coherent echo that surrounds the listener. Away from the centre, echoes become indistinct as sounds are no longer reflected from all sides of the circle at the same time. This would have created an acoustic emphasis at the centres of these circles.
I think the evidence for the intentional manipulation of sound at Avebury is quite strong. I was going to include Stone Henge at this point, however on further research I found that the Henge itself had been subject to a fair amount of disturbance so I decided to leave it out.
Almost all of the stones at Stonehenge have been artificially shaped. It was noted during the research that the inner surfaces of many stones were dressed to be either flat or concave. This is not visually striking, but could improve the ability of these stones to reflect sound. In contrast, the outward facing surfaces of the same stones are irregular or even convex. The enormous effort invested in dressing sarsens and bluestones into these subtle and barely visible shapes is difficult to explain, but it might suggest that the builders of the monument knew how to emphasise the movement of sound.
For a detailed look at an acoustical investigation, please go to:
AVEBURY ECHOES: Acoustical effects of the Avebury Henge, Wiltshire
Maeshowe Mainland, Orkney, Scotland, circa 3,000BC
Maeshowe on Orkney
Maeshowe is considered to be one of the finest architectural achievements of prehistoric Europe. The mound, 35m in diameter and 7m high, consists mostly of packed stones and clay, with an inner layer of stones around the chamber itself. This chambered cairn was constructed with great care, the large dressed slabs being carefully set together and finished. The chamber is 4.5m square and about the same in height. A tapered orthostat faces each corner buttress giving an impression of space and strength. The whole impression is of majesty and the idea of a "Neolithic cathedral" comes to mind.
The amazing Maeshowe mound
Because of the chamber's acoustic properties, a drummer or chanter within the tomb could appear to be surrounded by silence, while the sounds they created were emphasised at significant parts of the chamber.
This effect - zones of extreme high and low sound - is due to the interaction of standing sound waves in the prehistoric structure.
The loudest areas, it was found, seemed to concentrate around the tomb's side chambers, perhaps giving the impression of otherworldy sound coming from the realm of the dead.
Notable acoustical effects at Maeshowe
One of these is a phenomenon known as "standing waves." These result from the combination of two sound waves of equal frequency and intensity travelling in opposite directions, which can produce zones of low or high intensity as the waves interact, either cancelling each other out or combining to enhance the sound.
It is hard to say whether Maeshowe was intentionally designed to exhibit this phenomenon. However it’s extremely interesting to note the unusual design of the mound, drawing your attention to the side chambers that are ideal for the production of standing waves.
The design of the Maeshowe mound (a sealed chamber with a long neck) meant that it also displayed an effect called Helmholtz resonance.
Another remarkable phenomenon which can be created inside passage graves is known as "Helmholtz Resonance" - the sound created when you blow across the neck of a glass bottle. Passage graves and bottles share the same basic architecture: a chamber connected to the outside world by a long, narrow neck. To create the effect, people would have had to create a sound within the chamber at precisely the right pitch, as determined by the relative proportions of the chamber and passageway at each site. The larger the chamber, the lower the pitch needed to create the resonance effect.
This phenomenon is also known to produce infrasound, a possible explanation for human’s experiencing uncomfortable feelings of awe and uneasiness, sometimes interpreted as being supernatural in origin.
Many societies communicate with ancestors or spirit worlds through altered states of consciousness. Altered states can be achieved in many different ways, and often involve sound. At Maeshowe it is possible that people inside inadvertently generated infrasonic sounds that could exert a physiological or psychological influence upon. This results from the phenomenon of Helmholtz Resonance.
We’ll never know if this was intentional on the part of the builders of Maeshowe, I’d like to believe it was. But what is without question is the effect this would have had on visitors to the mound and on those participating in ceremonies or rituals within its recesses.
Sound scientist, Prof. Daniel Talma of the University of Malta explains: “At certain frequencies you have standing waves that emphasize each and other waves that de-emphasize each other. The idea that it was used thousands of years ago to create a certain trance — that’s what fascinates me.”More on this later!